An occasional ensure is thrown when opening Camera Anim assets. Generally, the issue occurs when opening the asset for a second time, but the repro rate is low, around 1/5.
Result:
Observe an ensure failure in the logs
[2016.08.21-15.49.31:836][589]LogOutputDevice:Error: === Handled ensure: === [2016.08.21-15.49.31:837][589]LogOutputDevice:Error: [2016.08.21-15.49.31:837][589]LogOutputDevice:Error: Ensure condition failed: AttachParent == nullptr || !AttachParent->AttachChildren.Contains(this) [File:D:\Main\Main_Stream\Engine\Source\Runtime\Engine\Private\Components\SceneComponent.cpp] [Line: 1415] [2016.08.21-15.49.31:838][589]LogOutputDevice:Error: SetupAttachment cannot be used once a component has already had AttachTo used to connect it to a parent. [2016.08.21-15.49.31:838][589]LogOutputDevice:Error: Stack: [2016.08.21-15.49.31:839][589]LogOutputDevice:Error: UE4Editor-Core.dll!FWindowsPlatformStackWalk::StackWalkAndDump() [d:\main\main_stream\engine\source\runtime\core\private\windows\windowsplatformstackwalk.cpp:183] [2016.08.21-15.49.31:839][589]LogOutputDevice:Error: UE4Editor-Core.dll!FDebug::EnsureFailed() [d:\main\main_stream\engine\source\runtime\core\private\misc\outputdevice.cpp:297] [2016.08.21-15.49.31:840][589]LogOutputDevice:Error: UE4Editor-Core.dll!FDebug::OptionallyLogFormattedEnsureMessageReturningFalse() [d:\main\main_stream\engine\source\runtime\core\private\misc\outputdevice.cpp:432] [2016.08.21-15.49.31:840][589]LogOutputDevice:Error: UE4Editor-Engine.dll!USceneComponent::SetupAttachment() [d:\main\main_stream\engine\source\runtime\engine\private\components\scenecomponent.cpp:1415] [2016.08.21-15.49.31:841][589]LogOutputDevice:Error: UE4Editor-Engine.dll!AMatineeActor::AMatineeActor() [d:\main\main_stream\engine\source\runtime\engine\private\interpolation.cpp:359] [2016.08.21-15.49.31:841][589]LogOutputDevice:Error: UE4Editor-Engine.dll!AMatineeActorCameraAnim::AMatineeActorCameraAnim() [d:\main\main_stream\engine\source\runtime\engine\private\interpolation.cpp:1868] [2016.08.21-15.49.31:842][589]LogOutputDevice:Error: UE4Editor-CoreUObject.dll!StaticConstructObject_Internal() [d:\main\main_stream\engine\source\runtime\coreuobject\private\uobject\uobjectglobals.cpp:3149] [2016.08.21-15.49.31:842][589]LogOutputDevice:Error: UE4Editor-Engine.dll!NewObject<AActor>() [d:\main\main_stream\engine\source\runtime\coreuobject\public\uobject\uobjectglobals.h:1211] [2016.08.21-15.49.31:843][589]LogOutputDevice:Error: UE4Editor-Engine.dll!UWorld::SpawnActor() [d:\main\main_stream\engine\source\runtime\engine\private\levelactor.cpp:412] [2016.08.21-15.49.31:843][589]LogOutputDevice:Error: UE4Editor-Engine.dll!UWorld::SpawnActor() [d:\main\main_stream\engine\source\runtime\engine\private\levelactor.cpp:271] [2016.08.21-15.49.31:844][589]LogOutputDevice:Error: UE4Editor-AssetTools.dll!FAssetTypeActions_CameraAnim::CreateMatineeActorForCameraAnim() [d:\main\main_stream\engine\source\developer\assettools\private\assettypeactions\assettypeactions_cameraanim.cpp:23] [2016.08.21-15.49.31:844][589]LogOutputDevice:Error: UE4Editor-AssetTools.dll!FAssetTypeActions_CameraAnim::OpenAssetEditor() [d:\main\main_stream\engine\source\developer\assettools\private\assettypeactions\assettypeactions_cameraanim.cpp:182] [2016.08.21-15.49.31:844][589]LogOutputDevice:Error: UE4Editor-UnrealEd.dll!FAssetEditorManager::OpenEditorForAsset() [d:\main\main_stream\engine\source\editor\unrealed\private\toolkits\asseteditormanager.cpp:338] [2016.08.21-15.49.31:845][589]LogOutputDevice:Error: UE4Editor-AssetTools.dll!FAssetTypeActions_Base::AssetsActivated() [d:\main\main_stream\engine\source\developer\assettools\public\assettypeactions_base.h:41] [2016.08.21-15.49.31:845][589]LogOutputDevice:Error: UE4Editor-ContentBrowser.dll!SContentBrowser::OnAssetsActivated() [d:\main\main_stream\engine\source\editor\contentbrowser\private\scontentbrowser.cpp:1813] [2016.08.21-15.49.31:846][589]LogOutputDevice:Error: UE4Editor-ContentBrowser.dll!TBaseSPMethodDelegateInstance<0,SContentBrowser,0,TTypeWrapper<void> __cdecl(TArray<FAssetData,FDefaultAllocator> const & __ptr64,enum EAssetTypeActivationMethod::Type)>::Execute() [d:\main\main_stream\engine\source\runtime\core\public\delegates\delegateinstancesimpl.h:317] [2016.08.21-15.49.31:846][589]LogOutputDevice:Error: UE4Editor-ContentBrowser.dll!TBaseSPMethodDelegateInstance<0,SContentBrowser,0,void __cdecl(TArray<FAssetData,FDefaultAllocator> const & __ptr64,enum EAssetTypeActivationMethod::Type)>::ExecuteIfSafe() [d:\main\main_stream\engine\source\runtime\core\public\delegates\delegateinstancesimpl.h:424] [2016.08.21-15.49.31:847][589]LogOutputDevice:Error: UE4Editor-ContentBrowser.dll!TBaseDelegate<void,TArray<FAssetData,FDefaultAllocator> const & __ptr64,enum EAssetTypeActivationMethod::Type>::ExecuteIfBound() [d:\main\main_stream\engine\source\runtime\core\public\delegates\delegatesignatureimpl.inl:608] [2016.08.21-15.49.31:848][589]LogOutputDevice:Error: UE4Editor-ContentBrowser.dll!SAssetView::OnListMouseButtonDoubleClick() [d:\main\main_stream\engine\source\editor\contentbrowser\private\sassetview.cpp:3555] [2016.08.21-15.49.31:848][589]LogOutputDevice:Error: UE4Editor-ContentBrowser.dll!TBaseSPMethodDelegateInstance<0,SAssetView,0,TTypeWrapper<void> __cdecl(TSharedPtr<FAssetViewItem,0>)>::Execute() [d:\main\main_stream\engine\source\runtime\core\public\delegates\delegateinstancesimpl.h:317] [2016.08.21-15.49.31:849][589]LogOutputDevice:Error: UE4Editor-ContentBrowser.dll!TBaseSPMethodDelegateInstance<0,SAssetView,0,void __cdecl(TSharedPtr<FAssetViewItem,0>)>::ExecuteIfSafe() [d:\main\main_stream\engine\source\runtime\core\public\delegates\delegateinstancesimpl.h:424] [2016.08.21-15.49.31:849][589]LogOutputDevice:Error: UE4Editor-ContentBrowser.dll!TBaseDelegate<void,TSharedPtr<FAssetViewItem,0> >::ExecuteIfBound() [d:\main\main_stream\engine\source\runtime\core\public\delegates\delegatesignatureimpl.inl:608] [2016.08.21-15.49.31:850][589]LogOutputDevice:Error: UE4Editor-ContentBrowser.dll!SListView<TSharedPtr<FAssetViewItem,0> >::Private_OnItemDoubleClicked() [d:\main\main_stream\engine\source\runtime\slate\public\widgets\views\slistview.h:718] [2016.08.21-15.49.31:850][589]LogOutputDevice:Error: UE4Editor-ContentBrowser.dll!STableRow<TSharedPtr<FAssetViewItem,0> >::OnMouseButtonDoubleClick() [d:\main\main_stream\engine\source\runtime\slate\public\widgets\views\stablerow.h:264] [2016.08.21-15.49.31:851][589]LogOutputDevice:Error: UE4Editor-Slate.dll!<lambda_eeb33fd1b480e3cad58a1531d90d2e14>::operator()() [d:\main\main_stream\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:5333] [2016.08.21-15.49.31:851][589]LogOutputDevice:Error: UE4Editor-Slate.dll!FEventRouter::Route<FReply,FEventRouter::FBubblePolicy,FPointerEvent,<lambda_eeb33fd1b480e3cad58a1531d90d2e14> >() [d:\main\main_stream\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:215] [2016.08.21-15.49.31:852][589]LogOutputDevice:Error: UE4Editor-Slate.dll!FSlateApplication::RoutePointerDoubleClickEvent() [d:\main\main_stream\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:5331] [2016.08.21-15.49.31:852][589]LogOutputDevice:Error: UE4Editor-Slate.dll!FSlateApplication::ProcessMouseButtonDoubleClickEvent() [d:\main\main_stream\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:5316] [2016.08.21-15.49.31:853][589]LogOutputDevice:Error: UE4Editor-Slate.dll!FSlateApplication::OnMouseDoubleClick() [d:\main\main_stream\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:5294] [2016.08.21-15.49.31:853][589]LogOutputDevice:Error: UE4Editor-Core.dll!FWindowsApplication::ProcessDeferredMessage() [d:\main\main_stream\engine\source\runtime\core\private\windows\windowsapplication.cpp:1635] [2016.08.21-15.49.31:854][589]LogOutputDevice:Error: UE4Editor-Core.dll!FWindowsApplication::DeferMessage() [d:\main\main_stream\engine\source\runtime\core\private\windows\windowsapplication.cpp:1977] [2016.08.21-15.49.31:854][589]LogOutputDevice:Error: UE4Editor-Core.dll!FWindowsApplication::ProcessMessage() [d:\main\main_stream\engine\source\runtime\core\private\windows\windowsapplication.cpp:750] [2016.08.21-15.49.31:855][589]LogOutputDevice:Error: UE4Editor-Core.dll!FWindowsApplication::AppWndProc() [d:\main\main_stream\engine\source\runtime\core\private\windows\windowsapplication.cpp:672] [2016.08.21-15.49.31:855][589]LogOutputDevice:Error: USER32.dll [2016.08.21-15.49.31:855][589]LogOutputDevice:Error: USER32.dll [2016.08.21-15.49.31:856][589]LogOutputDevice:Error: UE4Editor-Core.dll!FWindowsPlatformMisc::PumpMessages() [d:\main\main_stream\engine\source\runtime\core\private\windows\windowsplatformmisc.cpp:905] [2016.08.21-15.49.31:856][589]LogOutputDevice:Error: UE4Editor.exe!FEngineLoop::Tick() [d:\main\main_stream\engine\source\runtime\launch\private\launchengineloop.cpp:2795] [2016.08.21-15.49.31:857][589]LogOutputDevice:Error: UE4Editor.exe!GuardedMain() [d:\main\main_stream\engine\source\runtime\launch\private\launch.cpp:156] [2016.08.21-15.49.31:857][589]LogOutputDevice:Error: UE4Editor.exe!GuardedMainWrapper() [d:\main\main_stream\engine\source\runtime\launch\private\windows\launchwindows.cpp:126] [2016.08.21-15.49.31:858][589]LogOutputDevice:Error: UE4Editor.exe!WinMain() [d:\main\main_stream\engine\source\runtime\launch\private\windows\launchwindows.cpp:202] [2016.08.21-15.49.31:858][589]LogOutputDevice:Error: UE4Editor.exe!__scrt_common_main_seh() [f:\dd\vctools\crt\vcstartup\src\startup\exe_common.inl:264] [2016.08.21-15.49.31:859][589]LogOutputDevice:Error: kernel32.dll [2016.08.21-15.49.31:859][589]LogOutputDevice:Error: ntdll.dll [2016.08.21-15.49.31:859][589]LogOutputDevice:Error: ntdll.dll [2016.08.21-15.49.31:860][589]LogOutputDevice:Error:
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-35007 in the post.